To put it bluntly, yes - HID kits are illegal to fit to a car which is to be used on the road.

Although it is not mentioned anywhere they are illegal, they are against the The Road Vehicle Lighting Regulations 1989. Under these Regulations, HID/Gas Discharge/Xenon headlamps are not mentioned and therefore they are not permitted according to the strict letter of the law.

However new vehicles have HID headlamps. This is because they comply to European type approval Regulations. The UK cannot refuse to register a vehicle with a European type approval. These are to ECE Regulation 98 (for the HID headlamps which are tested on a rig in a laboratory) and ECE Regulation 48 (Lighting Installation on the vehicle).

For the after market, a used vehicle cannot obtain type approval because it is only applicable for new vehicles. However we feel that saying "HID is banned in the after market" would not be reasonable. Instead we should make analogies with new vehicles. It would be reasonable to require HID in the after market to meet the same safety standards as on new vehicles. The same level of safety should apply.

Therefore a HID headlamp unit sold in the after market should:

1. be type approved to ECE Regulation 98 as a component.

2. when fitted to the vehicle should enable ECE Regulation 48 to be complied with (although no government inspection will take place).

3. Comply with RVLR as far as "use" is concerned.

In practice this means:

1. The headlamp unit (outer lens, reflector, bulb) shall be type approved to ECE 98 and be "e-marked" to demonstrate this. That can only be done by the headlamp supplier - Hella, Valeo etc. who must test the headlamp in an independent laboratory.

2. Once fitted to the vehicle it must have headlamp cleaning and self-levelling (which can be for the headlamp or can be in the vehicle suspension - some expensive estate cars have "self-levelling suspension" and that is adequate). Also the dipped beam must stay on with the main beam.

3. The headlamp must be maintained in good working order, kept clean, and aligned/adjusted correctly like any other headlamp.

Under the Road Traffic Act 1988 it is an offence to supply, fit or use vehicle parts which are not legal.

In summary it is not permitted to convert an existing halogen headlamp unit for use with HID bulbs. The entire headlamp unit must be replaced with one designed and approved for use with HID bulbs and it must be installed in accordance with the rules stated above.

Info taken from This site

Although it is widely noted that HID kits look good and give greater vision to the user, they can be very dangerous to other road users as well as being illegal. Without the correct set up (non are available for the 206), there is no way of safely harnessing and focusing the light pattern, therefore leaving a high risk of dazzling other drivers.

It is also a magnet for being stopped by the Police who are taking a dim view of after market HIDs, and many forces throughout the UK will not only fine offenders but also seize their vehicles.